Protective DevicesANNUAL REPORT OF COMMITTEE ON PROTECTIVE DEVICES*

To the Board of Directors: The Relay Handbook was published in 1926 under theFollowing a custom established a number of years sponsorship of this committee and the Electrical

ago, all the work coming under the jurisdiction of the Apparatus Committee of the National Electric LightCommittee on Protective Devices has been divided Association. Developments since then have been ofamong subcommittees, accounts of whose activities sufficient importance to justify the publication ofare presented as part of this report and as evidence of material necessary to bring the Handbook up to date.what has been accomplished during the year. These The spirit of cooperation between the Subcommittee onsubcommittees, with their chairmen, are as follows: Relays and the corresponding subcommittee of The

1. Circuit Breakers, Switches and Fuses, National Electric Light Association has been mostA. M. Rossman, Sargent&Lundy, Inc., Chicago, III. gratifying, and at this time, your committee wishes to

2. Current Limiting Reactors and Resistors, express its appreciation to that organization for theN. L. Pollard, United Engineers & Constructors, privilege of joining in this work which promises toNewark, New Jersey. produce such good results.

3. Lightning Arresters, Herman Halperin, The revision of the lightning arrester standards hasCommonwealth Edison Company, Chicago, III. been a particularly difficult task, both because of the

4. Relays, H. P. Sleeper, Public Service Elec- rapidity of development of this class of equipment andtric & Gas Co., Newark, New Jersey. because of new methods of research which result in a

Except for the disbanding of one subcommittee, the continuous uncovering of new facts and the formationorganization was the same as that of the preceding year. of new theories. Excellent progress has been made,The subcommittee on Industrial Equipment and however, as is indicated in the report of the subcom-Service Protection, which functioned in 1928-1929 mittee on lightning arresters, included in this report.reported at the beginning of the year that its work was Progress may ajso be reported in the preparation ofcomplete. This subcommittee was therefore dis- standards for fuses. It is expected that the succeedingcontinued with the understanding that features of committee can readily prepare these for presentation toprotection affecting industrial equipment and service the Standards Committee during the coming year.would be followed in a general way by the main com- A revision of the section of standards covering dis-mittee. connecting switches is now under way and progress isThe work of the subcommittees during the past year reported. This revision will include knife switches in

has followed three established lines: its scope.1. Arranging for and following through the The question of standards for fault current-limiting

preparation of papers for presentation before the devices was given consideration and a recommendationInstitute. covering this is made in a following subcommittee

2. Revision of existing, and preparation of new, report.standards. INTERCONNECTION AND STABILITY FACTORS

3. A survey and review of research and devel- Early in the year your committee was asked to giveopment during the year in those things over which consideration to the formation of a joint subcommitteethe committee has jurisdiction. to study the problem of interconnection and stability

REVISION AND PREPARATION OF PUBLICATIONS factors. It was proposed that this subcommittee beAND STANDARDS made up of members selected from the committees on

Perhaps the greatest activity has been shown in the Power Transmission and Distribution, Power Genera-matter of preparing a supplement to the Relay Hand- tion, and Protective Devices. This proposal wasbook and in revising the proposed Standards on Light- endorsed by your Committee and it is recommendedning ArTesters. that the organization be set up early in the coming year.*COMMITTEE ON PROTECTIVE DEVICES: MEETINGS

E. A. Hester, Chairman, The practise of having all the work covered by sub-Raymond Bailey, Vice-Chairman,L. E. Frost, Secretary, committees has resulted in simplifying the work of the3. E. Allen, F. C. HIanker, A. M. Rossman, main committee, in that it reduces to a minimum theL. N. Blagoveschensky, L. F. Hickernell, C. H. Sanderson,A. C. CDummins, J. Allen Johnson, A. H. Schirmer, number of main committee meetings.H. W. Drake, M. G. Lloyd. H. P. Sleeper, Two meetings, only, were held this year, the firstW. S. Edsall, J. B. MacNeil,t R. M. Spurck,E. E. George, 3. P. McKearin, E. R. StaufYacher, for purposes of organization, and the second at the endH[. Halperin, R. C. Mulr, H. R. Summerhayes. of the year for review of the work of the subcommittees.

Presented at the N.L.me Pollrd,nino h . .E . oot It has been found that the smaller groups can workOntariSumme Conventio of te A.I. E. Tornto much more efficiently, and that the reduction in the

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Oct. 1930 PROTECTIVE DEVICES 1755

number of main committee meetings is a decided is evidenced by the increasing purchases of this type ofadvantage. switchgear by those companies which have had the

It is interesting to observe that another advantage greatest amount of experience with it.has developed from this method of handling committee One of the outstanding installations of this kind ofwork. The chairmen of the subcommittees are usually switching equipment was made at the State Linechosen from the main committee, but its members maY Generating Station in Chicago. A complete descrip-be drawn from the general membership of the Institute. tion of this installation, together with a recitation of theThis has proved an excellent way to initiate younger factors influencing the choice and design, was pre-members of the Institute into technical committee work, sented by Mr. A. M. Rossman at the 1930 Winter Con-and actually creates an enthusiasm for it. Conse- vention in a paper entitled Metal-Clad Switchgear atquently, there is always available a number of members the State Line Power Station.who are going through a training process, and appoint- In the matter of standards, it is likely that thement to a main committee does not find them entirely revision covering the section on disconnecting switchesunprepared. will be submitted to the Standards Committee before

REPORTS OF SUBCOMMITTEES the expiration of the current committee year. In re-On Circuit Breakers, Switches, and Fuses.* During the vising this section, a division on knife switches which

past year, much time and study have been devoted has not heretofore been covered by the standards isto research in oil circuit breaker design. A large being included.part of this effort has been aimed at the discovery Work is progressing on a draft of standards forof the fundamental laws which govern the formation, fuses. This probably will not be completed this yearcontrol, and breaking of anelectric arcunderoil. These and it is recommended that the succeeding subcommit-studies led to the development of the deion grid for tee continue actively in all this standards work.controlling the arc in a high-voltage oil circuit breaker, A number of organizations are engaged in formulatingprobably the outstanding achievement of the year in standards and definitions for circuit breakers,oil circuit breaker design. The theory of the deion grid, switches, and fuses, as well as for accessory equipment.the method of adapting it to oil circuit breakers, and Chief, among these are the N. E. L. A., A. S. A.,test data from experiments conducted on oil circuit N. E. M. A. and A. E. I. C. It is recommended thatbreakers equipped with these grids, were ably presented the succeeding subcommittee determine and classifyat the Winter Convention oftheA. I. E. E. in two papers; the activities, and coordinate its work with theseExtinction of a Long A-c. Arc, by Dr. Joseph Slepian groups in order to avoid duplication.and Use of Oil in Arc Rupturing, by Messrs. B. P. On Current-Limiting Reactors and Resistors.* TheBaker and H. M. Wilcox. The tests presented in these Sub-committee on Current-Limiting Reactors and Re-papers show that the addition of deion grids to an oilcircuit breaker of moderate operating speed reduces the sistors has this year sponsored the preparation of papers

t on reactor and resistor subjects and has studied thedimeofarcing,increasesthe g *tmutebe dissipat ing,the question of revising and enlarging the standardizationdecreases the energy that mustp eid ssipated during the work relating to subjects coming under its jurisdic-interrupting.p.ocess tion. The following papers prepared under its auspicesThe demand for more rapid clearing of short circuits, were presented at the North Eastern District Meeting,to increase the stability limits of transmission systems, Springfield, Mass., May 7-10, 1930:

has stimulated the development of high-speed oilcircuit breakers. During the year, two manufacturers Shunt Resistorsfor Reactors, by L. V. Bewley, F. H.of this equipment have announced designs of circuit Kierstead, and H L Rordenbreakers capable of interrupting circuits of voltages up Arcing Grounds and Effect of Neutral Groundingto 230,000 volts in eight cycles after the trip-coil is ener- Impedance, by J. E. Clem.gized. Field tests have been made, as high as 230,000 Carrying out an assignment made at the beginning ofvolts demonstrating the claims made by these manu- the year, the subcommittee secured representativefacturers. opinion as to the desirability of enlarging the scope of

Interest in metal-clad switchgear is growing as its the A. I. E. E. Standards to cover, in one section,advantages are becoming better known. The past all fault current-limiting devices, such as reactors andyear has seen refinements in design and a steady in- resistors and possibly grounding transformers. It iscrease in production. The trend is very definitely possible that the little use made of grounding resistorstoward standardized forms which should lead to mass may not justify the effort necessary to work them intoproduction methods in manufacture and substantial the standards. It is recommended, however, thatreductions in price. So far, operating experience with definite steps be taken to cover in one section themetal-clad switchgear has justified the expectations other devices mentioned, and at such time give furtherof both designing engineers and operating engineers as consideration to grounding resistors and transformers.

*A. M. Rossman, Chairman. *N. L. Pollard, Chairman.

1756 PROTECTIVE DEVICES Transactions A. I. E. E.

Several years ago, the Committee on Protective Artificial Lightning Surges, by McEachron, Hem-Devices made an exhaustive study of the general sub- street and Rudge.2ject of the grounding of neutrals on power systems. Lightning Investigation on 220-Kv. System of Pennsyl-This work was done under the direction of a special sub- vania Power and Light Company, by Smeloff and Price.2committee and resulted in a number of excellent papers Lightning Investigation on Ohio Power Companyon the subject being presented before the Institute in System, by Sporn and Lloyd, Jr.21922 and 1923. The study having been concluded, the Lightning Investigation on Transmission Lines, bysubcommittee was disbanded, since which time the Lewis and Foust.2subject has been followed in its general aspects by the Effect of Transient Voltages on Power Transformermain committee. Design, by Palueff.2

This year, the question was raised as to whether Still other instructive papers on the subject can bethere had been sufficient development during the past found in the following publications:six or seven years to warrant another study of the same "Lightning Arrester and Factors Affecting Its Per-kind. There was enough uncertainty to cause doubt, formance and Application," by Towne, G. E. Review,so the Subcommittee on Current-Limiting Reactors and August 1929.Resistors was asked to investigate and recommend as to "The Ideal Lightning Arrester, What is It, Can Itwhether or not the subcommittee should be reorganized. Be Produced?" by Atherton, Electrical Journal, August

Obviously this is a matter which will be of vital 1929.v

.interest to other A. I. E. E. technical committees, Several very excellent artieles onElghtning and pro-particularly those on Power Transmission and Dis- tection problems have appeared in European magazines,tribution, and Power Generation. Since it is believed among them Sthat developments over the past few years have intro- "The Present Status of the Problem of Lightningduced new factors into the problem of grounding, it is Protection, by Matthias, Elektrotechnische Zeitschrift,recommended that the joint subcommittee referred to October 1929.elsewhere in this report include this subject in its "Protection of Electrical Systems against Over-duties. This recommendation has been endorsed by the Voltages" (Report of Electrical Institute of Technologymain committeeand transmittedtto the chairmenof the College Aachen), by Flegler, Elektrotechnische Zeit-two other committees concerned. schrift, January, 1930.

"Over-Voltages in Electrical Systems," by Berger,On Lightning Arresters.* In the past year, work has Bulletin of Schweizerischer Electrotechinscher Verein,been done to determine the effects of lightning on trans- February-March, 1930.mission and distribution circuits, and to provide experi- In all these articles many conclusions are drawn con-mental and commercial forms of protection. Field firming findings by investigators in this country.studies of natural and artificial lightning were made by In the field studies on overhead transmission linesseveral investigators using high-grade forms of recording d t l sg during the lightning season of 1928, only two oscillo-devices. The new developments included arresters- . .............................. grams were obtained of natural lightning. In 1929which were installed experimentally on transmission g w oline towers. over two hundred such oscillograms were obtained,greatly increasing our knowledge of the magnitude andMuch of the progress during the last year is well wave shape of lightning surges on transmission lines.

described in several valuable papers which have been Numerous records were obtained of artificial surgespresented before the Institute, among which the follow- applied to overhead lines, the lines being terminateding may be mentioned :' with various apparatus or connections or in series with

Development of New Autovalve Arrester, by Slepian, underground cables. Since the findings of these variousTanberg, and Krause.' tests have been so thoroughly described in the articles

Thyrite, A New Material for Lightning Arresters, by listed above as well as summarized in various electricalMcEachron.1 journals, they need not be repeated here.

Cathode Ray Oscillograph Studies of Lightning on For distribution circuits, experiences of severalTransmission Lines, by Cox and Beck.2 utilities indicate that the proper use of lightning ar-Surge Characteristics of Insulators and Gaps, by resters reduces the number of transformer failures by 50

Torok.2 to 90 per cent, depending on the nature of the lightningLsightning Investigations on Lsines of Public Servwice in the given locality and the nature of the equipment.

Electric & Gas Company, by Conwell and Fortescue.2 In general, it has been found that the older transformers,Lightning Voltages on Transmission Ljines, by George which are usually of the smaller sizes and have smaller

and Eaton.2 clearances between leads and case and over the bushings,t Study of Traveling Waves on Transmission Lines with are more susceptible to failure due to lightning than the*HermanHalperin, Chairman, newer transformers. One company found that trans-1. A. I. E. E. Quarterly TRANS., April and July, 1930. formers from 15 to 25 years old had a rate of failure2. A. I. E. E.TRANS., July, 1930.- due to lightning several times the rate for trans-

Oct. 1930 PROTECTIVE DEVICES 1757

formers made in the last five years. Three years ago such additional technical information as will no doubtthis company revised its specifications for 2080- to become available. In view of this outlook, it seems230/115-volt distribution transformers, improving the advisable to have the advantage of the use of the pro-arrangement of the leads and increasing the flashover posed standards in the meantime.voltages of the leads to case and over the bushings. It is recommended that the succeeding subcommitteeOver two thousand of these transformers were in service actively pursue the adoption of these standards.in 1929 and not one failed due to lightning. It is further recommended that the subcommittee,The Commonwealth Edison Company has continued (1) study a standard test surge and the surge which

the investigations of lightning damage on its distribu- should be applied in the duty cycle test; (2) investi-tion system as described in previous reports. Last year gate the value of merit of low-resistance grounds, (a,a detailed study was made of transformer locations on distribution systems, and b, on transmissionadjacent to points where transformers failed due to systems); and (3) investigate the effect of "repeatedlightning, and the many possible factors of such ad- flash" in lightning stroke on arrester characteristics.jacent points correlated in an attempt to discover the On Relays.* The efforts of this subcommittee havefactors causing the failure to occur on the particular been directed into three channels as follows:transformer. No new factors of importance were 1. The completion of the Standards for Relays,discovered. The previous findings were verified;thatis, begun by the previous subcommittee.that old transformers and transformers with poor bush- 2. The preparation of a supplement to the Relayings and lead clearances are those most likely to fail. Handbook.Furthermore, there appears to be a peculiar tendency for 3. The preparation of a series of papers on thefailures to occur in greater numbers than is a fair pro- subject of relays for presentation before theportion at locations where the ground resistance is less Institute.than 20 ohms. Incidentally, 99 per cent of all the The previous subcommittee completed the prepara-ground resistance in the area studied is less than 75 tion of a set of tentative standards and presented it toohms. This tendency is not what would be expected the Standards Committee for consideration. Recently,from laboratory tests and is not in agreement with Working Committee No. 48 was appointed by thecertain data obtained on some other systems. Studies Standards Committee, with Mr. George Sutherland asare being continued. Chairman, and certain members of this subcommitteeAn extensive klydonograph investigation has been were appointed on the working committee to assist in

made by the American Telephone and Telegraph Com- the preparation of a final draft of these standards. Thepany on communication circuits. Some of the most part played by this subcommittee consisted largely,interesting findings were that the capacity of the pro- therefore, of assistance rendered to Mr. Sutherland'stector ground to earth is generally more important committee. It is expected that a final draft of thesethan its resistance; that practically all the potential standards will be available for distribution this year.drop in a protector circuit was between the ground rod The most important work of the year has been theand the earth; that conductor potentials and sheath preparation of a supplement to the Relay Handbook.potential are nearly equalized a short distance inside a To carry out this work, a joint subcommittee waslead-sheathed telephone cable regardless of length of appointed whose members are representatives of theoutside conductor exposure; and that large differences, relay subcommittee and of the correspondingeven opposite polarity of induced potentials, can exist N. E. L. A. group. The present edition of the Relayin the same overhead wire within short distances. Handbook was published in 1926 under the same aus-One of the chief accomplishments of this subcom- pices, and it was felt that the development in design and

mittee in the past year has been the revision of the application of protective relays during the subsequentproposed Standards for Lightning Arresters. Much four year period has been sufficient to warrant thetime has been spent on this work and it is believed that addition of new material to the original publication.the proposed preliminary Standards are in such good The first consideration was to decide upon a method ofshape that in 1930 they may be adopted with only minor adding this new material, the two obvious coursesrevisions. being first, to rewrite completely the Handbook and

Standard laboratory waves have been incorporated in bring all chapters up-to-date, and, second, to review thethese proposed standards for testing arresters. These present book and present the revisions and additions inwaves have been made as severe as possible up to the the form of a supplement. It was finally decided tolimit of the laboratory testing equipment, in preference follow the second course, publishing a supplement toto a simulation of any particular lightning wave, the existing book. Factors affecting this decision were

It is hoped that an active interest will be taken in as follows:these proposed standards. Probably after the experi- 1. To rewrite the old book would require at leastence of a few years it will become feasible to revise them a year's time, including,. that necessary forand incorporate additional paragraphs, making use of *11. P. Sleeper, Chairman.

1758 PROTECTIVE DEVICES Transactions A. I. E. E.

publication, while a supplement could be pre- more, during the past few years the use of ground orpared in a relatively short time. zero-phase sequence relaying has developed rapidly and

2. The supplement can be published and sold results and possibilities both deserve more publicity.separately for a small sum and can be added to Indications are that both of these phases of protectivefurther editions of the present handbook at no relaying have an extensive future ahead.appreciable additional cost. The paper Transmission System Relay Protection,

3. The stock of the existing handbooks is now Part III, may be regarded as a'sequel to two otherpractically exhausted and it was felt that a papers which have been presented before the Institute.reprinting should not be made until such new ma- The first of these was written by Messrs. Woodrow,terials as is available has been added insomeform. Roper, Traver, and MacGahan in 'June, 1919. The

4. The immediate preparation of a supplement second, presented at Niagara Falls in June, 1922, waswould enable the stock to be replenished in an the work of Messrs. Hester, Traver, Conwell andup-to-date form, whereas at least a year would Crichton. Each of these gave a concise summary ofelapse before new stock could be obtained con- current relay practise up to the date indicated, and thetaining the new material if rewriting was at- paper presented this year is designed to bring the sub-tempted. ject up-to-date for Institute records. The scope of

The joint subcommittee therefore proceeded with this last paper has been broadened to some extent andthe preparation of the supplement instead of a revision, includes relays and relaying for both apparatus and

the pertnoteupmnisaotransmission lines.The present book was carefully reviewed, necessarycorrections made, obsolescent material omitted, and the It iS not necessary in this report to attempt to sum-newest developments added. Fortunately, but few marize new developments, since the symposium pre-revisions were found to be necessary and the supplement sented at Toronto completely covers the subject.proved to be just what the name implied, added ma- It would seem fitting, however, to make brief mentionterial. Both the manufacturing and operating engi- of the trend in the art as indicated by the latest de-neers have cooperated wholeheartedly, and it is felt velopments The major part of the effort expended inthat all material which will be of value has been in- development work during the past year or so seems tocluded in the new publication. The final report 'of this be towards the reduction of time element or the develop-joint subcommittee has been submitted to the main ment of so-called "high-speed relays." For the pastcommittee for approval and with recommendations for ten years, the so-called "time element relaying" haspublication. been accepted rather generally as the solution to pro-The subcommittee has been quite active in the tection problems. However, with the advent of high-

voltage interconnections, the instantaneous discon-preparation of the following papers being presented at n I

the SummerConvetion in Toronto:nection of system faults has assumed vital importance.'Where seconds have been acceptable, a few cycles areDirectional Ground Relays, by E. E. George and now often the maximum which can be'allowed to main-

R . ,H*. -Ben.n*t*, Jr. tamn system stability. The speed of operation of cir-High-Speed Relaying, by L. N. Crichton. cuit breakers has been reduced materially 'and it is ob-Modern Requirements for Protective Relays on Impor- vious that relays must follow suit. Many forms of

tant System Interconnections, by 0. C. Traver, and these high-speed relays are now in- commercial use,L. F. Kennedy. some of them being entirely new developments and

Transmission System Relay Protection, Part III, by some of them being evolutions of existing time elementW. W. Edson. design.Problem of Service Security in Large Transmission It cannot be said that the use of time element relays

Systems, by Paul Ackerman. has been, or will be, entirely superseded. They willThe last symposium on the subject of relays was held probably always be of use in some form, and indispen-

at the Pittsburgh meeting in 1923. Since then, many sable for certain applications-such as back-up protec-papers on relays have been presented in mixed sessions tion. It is certain, however that the benefits to bebut no concerted effort has been made to bring the derived from the reduction of time in relay and breakerInstitute records in the art up-to-date. It was felt that operation are of sufficient value to justify the generalthe present time was particularly appropriate for -this use of high-speed relays.by reason of the revision work being done on the Relay In order that the Institute may have a complete'Handbook. An additional reason for holding a sympo- record of the development and use? of these high-speed'sium at this time is that a new era in protective relay relays, it is recommended that the succeeding sub-developments seems to be approaching. This is called committee follow the symposium at Toronto with"High-Speed Relaying" and is the subject of two of the papers on the application of high-speed relays and theirpapers scheduled for the Toronto meeting. Further- effect on interconnection and system stability.